No you can sing them anytime at all but some people believe it is bad luck to sing them when it is not Christmas so it depends in whether you believe in bad luck or not
because they are CHRISTMAS carols and people sing them only on Christmas Day! More detail: Christmas carols are sung and played throughout the Christmas season to celebrate the birth of Jesus, and to...
In part of the book when Scrooge is still mean, a caroler comes to his window and sings a carol in hope of food. Scrooge in turn throws a something at him and shoos him away.